Abstract: A device for predicting remaining capacity of a battery and a method for the same are disclosed. The device is embedded in a battery pack or externally coupled thereto. The device includes a program for proceeding an algorithm of cell capacity calculation, a database stored in a non-volatile memory having a table of open-circuit voltage, a table of current gain and a capacity conversion equation. The program generates a discharging curve according to the cell temperature and load accessed and corrects the database according to the battery voltage and the discharging curve and the coulomb counter.